1. Field of the Invention
It is well known in the art that alkanesulfonates can be prepared by adding bisulfite to an olefin in a liquid reaction medium in the presence of a free radical initiating agent. Two methods of preparing alkanesulfonates have been cited in the past where (1) all the reactants are charged together, hereinafter referred to as "Dump In" or "Charged Together" method and (2) where a prepared sodium bisulfite solution is added continuously, over a two to four hour period, to a solution comprising an alpha olefin, cosolvent, and free radical initiator. A discussion of the prior art relative to the above-mentioned processes will be discussed in detail elsewhere in the specification. Needless to say, the prior art in varying degrees discusses the importance of controlling such things as pH, reflux conditions, maintenance of no more than two phases of reaction mixture, and so forth. Applicants know of no process, however, that will be practical for the production of alkanesulfonates where the olefin is added to a bisulfite solution consisting essentially of cosolvent and free radical initiator. Contrary to the teachings of the prior art, applicants have found that alkanesulfonates can be prepared by adding alpha olefins to a sodium bisulfite solution comprising water and an aliphatic organic hydroxyl-containing compound, such as isopropanol, in the presence of a free radical initiator. Stated succintly, as opposed to the prior art processes enumerated above, the instant process is accomplished by the addition of olefin to a bisulfite solution.
The novel and unobvious aspects of the instant invention can be more readily appreciated and understood by a discussion of the knowledge of the art heretofore.
2. The Prior Art
U.S. Pat. No. 2,398,426
Discloses the preparation of alkanesulfonic acids and their salts from salts of sulfurous acid and olefins of less than four carbon atoms. The method is accomplished by reacting the olefin with a water-soluble salt of sulfurous acid at a temperature of 90.degree. C. to 200.degree. C. and a pressure of at least 400 atmospheres. More specifically, all reactants, exclusive of the olefin, are charged to a vessel, the vessel closed and mounted on a shaker machine. The system is pressured with sufficient olefin to give approximately the required pressure at the desired reaction temperature.
U.S. Pat. No. 2,504,411
Discloses the preparation of alkanesulfonates using peroxide catalysts and polar organic mutual solvents selected from alcohols, cyclic diethers, and organic amines. The method is accomplished by heating in a closed vessel the olefin and bisulfite in the presence of the peroxide and mutual solvent at a temperature of from 50.degree. C. to 200.degree. C.
U.S. Pat. No. 3,084,186
Discloses the preparation of alkanesulfonates whereby not more than two liquid phases, i.e. an oil phase and an aqueous phase, are maintained by a controlled gradual addition of bisulfite ion at a rate approximately equal to its rate of consumption during the course of reaction until at least the stoichiometric amount of bisulfite ion has reacted with the olefin. The method is accomplished by introducing olefin and bisulfite ion into the reaction zone in the presence of polar solvent and reaction initiating agent under sulfitation conditions, in a mol ratio of bisulfite ion to olefin of about 0.05 to 0.25 whereby a two liquid phase reaction medium is formed, further introducing into the reaction zone during the course of reaction additional bisulfite ion at a rate such as to maintain an amount of unreacted bisulfite ion in the reaction zone within the range of 0.05 to 0.25 mole per mole of original olefin introduced and continuing the addition of bisulfite ion at least until the stoichiometric amount of bisulfite has been reached.
U.S. Pat. No. 3,275,681
Discloses the preparation of alkanesulfonates using as catalyst a combination of a peroxide and an organometal salt. The method is accomplished by dissolving the bisulfite in water, the olefin in an organic solvent along with the peroxide and organometal. The two solutions are mixed and stirred for the period of time required to give the desired yield.
U.S. Pat. No. 3,522,297
Discloses the preparation of alkanesulfonates wherein the process is accomplished by preaerating the olefin with an oxygen containing gas and then reacting a non-interfering bisulfite with the preaerated olefin.
U.S. Pat. No. 3,541,140
Discloses the separation of alkanesulfonate product from the reaction mixture by maintaining a critical alcohol to water ratio and a critical temperature range.
U.S. Pat. No. 3,558,693
Discloses the preparation of a quaternary ammonium alkylsulfonate wherein a tetraalkylammonium bisulfite is used as the source of bisulfite ions. This bisulfite ion is formed in situ from a reaction mixture comprising anhydrous solvent, sulfur dioxide, quaternary ammonium hydroxide. The olefin and initiator are added to this mixture. All reactants are used from the beginning and in a single addition.
U.S. Pat. No. 3,644,499
Discloses the stabilization of organic sulfonates, prepared by conventional means, by the use of a combination of water, oxygen and an alkaline compound.